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Message-ID: <545FF8B5.5000007@lge.com>
Date: Mon, 10 Nov 2014 08:28:53 +0900
From: Gioh Kim <gioh.kim@....com>
To: Joonsoo Kim <iamjoonsoo.kim@....com>,
Andrew Morton <akpm@...ux-foundation.org>
CC: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Rik van Riel <riel@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Mel Gorman <mgorman@...e.de>,
Johannes Weiner <hannes@...xchg.org>,
Minchan Kim <minchan@...nel.org>,
Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
Zhang Yanfei <zhangyanfei@...fujitsu.com>,
Tang Chen <tangchen@...fujitsu.com>,
Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
Wen Congyang <wency@...fujitsu.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Michal Nazarewicz <mina86@...a86.com>,
Laura Abbott <lauraa@...eaurora.org>,
Heesub Shin <heesub.shin@...sung.com>,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
Ritesh Harjani <ritesh.list@...il.com>,
t.stanislaws@...sung.com, Vlastimil Babka <vbabka@...e.cz>,
linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mm/debug-pagealloc: cleanup page guard code
2014-11-07 ¿ÀÈÄ 4:35¿¡ Joonsoo Kim ÀÌ(°¡) ¾´ ±Û:
> Page guard is used by debug-pagealloc feature. Currently,
> it is open-coded, but, I think that more abstraction of it makes
> core page allocator code more readable.
>
> There is no functional difference.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
> ---
> mm/page_alloc.c | 38 +++++++++++++++++++-------------------
> 1 file changed, 19 insertions(+), 19 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index d673f64..c0dbede 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -440,18 +440,29 @@ static int __init debug_guardpage_minorder_setup(char *buf)
> }
> __setup("debug_guardpage_minorder=", debug_guardpage_minorder_setup);
>
> -static inline void set_page_guard_flag(struct page *page)
> +static inline void set_page_guard(struct zone *zone, struct page *page,
> + unsigned int order, int migratetype)
> {
> __set_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags);
> + INIT_LIST_HEAD(&page->lru);
> + set_page_private(page, order);
> + /* Guard pages are not available for any usage */
> + __mod_zone_freepage_state(zone, -(1 << order), migratetype);
> }
>
> -static inline void clear_page_guard_flag(struct page *page)
> +static inline void clear_page_guard(struct zone *zone, struct page *page,
> + unsigned int order, int migratetype)
> {
> __clear_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags);
> + set_page_private(page, 0);
> + if (!is_migrate_isolate(migratetype))
> + __mod_zone_freepage_state(zone, (1 << order), migratetype);
> }
> #else
> -static inline void set_page_guard_flag(struct page *page) { }
> -static inline void clear_page_guard_flag(struct page *page) { }
> +static inline void set_page_guard(struct zone *zone, struct page *page,
> + unsigned int order, int migratetype) {}
> +static inline void clear_page_guard(struct zone *zone, struct page *page,
> + unsigned int order, int migratetype) {}
> #endif
>
> static inline void set_page_order(struct page *page, unsigned int order)
> @@ -582,12 +593,7 @@ static inline void __free_one_page(struct page *page,
> * merge with it and move up one order.
> */
> if (page_is_guard(buddy)) {
> - clear_page_guard_flag(buddy);
> - set_page_private(buddy, 0);
> - if (!is_migrate_isolate(migratetype)) {
> - __mod_zone_freepage_state(zone, 1 << order,
> - migratetype);
> - }
> + clear_page_guard(zone, buddy, order, migratetype);
> } else {
> list_del(&buddy->lru);
> zone->free_area[order].nr_free--;
> @@ -862,23 +868,17 @@ static inline void expand(struct zone *zone, struct page *page,
> size >>= 1;
> VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);
>
> -#ifdef CONFIG_DEBUG_PAGEALLOC
> - if (high < debug_guardpage_minorder()) {
> + if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC) &&
> + high < debug_guardpage_minorder()) {
> /*
> * Mark as guard pages (or page), that will allow to
> * merge back to allocator when buddy will be freed.
> * Corresponding page table entries will not be touched,
> * pages will stay not present in virtual address space
> */
> - INIT_LIST_HEAD(&page[size].lru);
> - set_page_guard_flag(&page[size]);
> - set_page_private(&page[size], high);
> - /* Guard pages are not available for any usage */
> - __mod_zone_freepage_state(zone, -(1 << high),
> - migratetype);
> + set_page_guard(zone, &page[size], high, migratetype);
> continue;
> }
> -#endif
> list_add(&page[size].lru, &area->free_list[migratetype]);
> area->nr_free++;
> set_page_order(&page[size], high);
>
Looks good!
Thanks for your work.
--
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